Growing Hydroponic Sunflowers

Hydroponic Sunflowers
Difficulty Light EC Range pH Range: Time to Harvest
Intermediate 16 hours 1.2 -1.8 5.5 -6.8 2-3 months to bloom. Additional 1-2 months for seeds.
Nutrient and Health Info - Your guess is as good as mine.
Tips & Tricks - Sunflowers are self pollinating, however they don't mind a little help, such as a fan blowing air around them. Sunflower heads are ready for harvesting when the back of the flower turns from a bright green color to a dark yellow and/or brown color. The sunflower head will also droop.


Sunflowers are a beautiful addition to any garden, indoors or out.  There are nearly 70 different species of sunflower, including dwarf varieties for your indoor garden like the Sunny Smile, Sundance Kid, Little Becka, Pacino, and Suntastic Yellow.  Most sunflower varieties are easy to grow, both in soil and hydroponically.

Their delicious seeds are craved by children (young and old) and baseball players everywhere.  But, if you are growing sunflowers so that you can enjoy their seeds, make sure not to purchase seedless or pollenless sunflowers, like Sunny Smile.  There are many uses for the seeds, of course.  You can roast them and use them in dips, breads, muffins, salads, sauces and entrees.  Some will even steam the sunflower buds, or grill the whole sunflower head when it’s grown!

At any rate, whenever you grow sunflowers, you’re in for a beautiful and fun experience.


Growing sunflowers from seed is not typically difficult.  If you use your Seedling Starter Kit, you are likely to see sprouts in 4-6 days.  If you grow them directly in your iHarvest® or other hydroponic system, it is more likely to require 7-10 days for germination.


There are no big surprises here.  Sunflowers love plenty of light, so give them 16 hours of artificial light per day when growing indoors.  Your sunflower plant will grow and flower more quickly with more light.  But resist the temptation of giving your sunflower more than 16 hours of light.  Your plants need time to rest/sleep as well, and too much light means too little sleep.  Too little sleep can lead to less productivity and even disease.

EC Range:

Sunflowers enjoy healthy amounts of nutrients.  It will enjoy an EC of 1.2-1.6 prior to producing flower buds, but higher EC’s of 1.4-1.8 can be best when your sunflower is ready to flower.  And, when your flowers begin to grow, adding ½ of a nutrient flowering solution to ½ of a vegetation mix will give your sunflower the extra phosphorous it wants for optimum growth.

pH Range:

No surprises here either.  Keep your pH between 5.5-6.8 for optimal growth.


Sunflowers are typically considered self-pollinating.  But giving them a little bit of extra help never hurts.  Many self-fertile plants like tomatoes and peppers need only a fan in front of them, or a little shake of their stem to achieve pollination.  Sunflowers, like strawberries, can use the frequent help of a small paint or makeup brush for best results.  Simply brush the disk of the sunflower all around to spread pollen around maximize seed production later.

Sunflowers develop from the outside in, so pollinating them over time is best.  This is how seeds will develop as well, with inner seeds being the last to develop.  Sometimes, the center parts of the sunflower will not develop and produce seeds.

Time To Harvest:

It generally takes a sunflower 80 - 120 days to bloom, from seedling stage.  Most varieties bloom for an additional 8-12 weeks before they are ready to be harvested and dried.

Pruning and Harvesting:

Sunflower heads are ripe and ready for harvesting when the back of the flower turns from a bright green color to a dark yellow and/or brown color, and their yellow peddles on the front begin to die off.  Often, especially for sunflowers with larger heads, the sunflower head will droop when it is ready to be harvested. 

If you’d like to harvest sunflower seeds, now is the time to cut off the sunflower head and let it dry out in a warm, ventilated area where it won’t attract rodents or birds.  Typically, it takes 2-4 weeks for the heads to cure.  When it is cured, it will be dark brown.  The seeds will be dry enough to be lightly scraped off into a large bowl or bucket.  If you have two sunflower seeds heads, you can rub them together to knock the seeds loose.  Place the seeds in a single layer on a flat surface and continue to let them dry out for a few days longer, after removing them from the heads.  When completely dry, you can store then in an airtight container for 1-2 months before use.  Storing them in the refrigerator will help them last longer.

Preparing Roasted Sunflower Seeds:

Let your sunflower seeds soak in a pot of water for 8-10 hours, or bring the pot to a boil and let it simmer for 1-2 hours.  Add salt as desired (more is typically better for taste, and less is better for health).  Drain the seeds with a colander (but do not rinse them if they are salted) and then dry them on a paper towel.  Place them on a baking sheet, and place in an oven preheated to 325° for 25-35 minutes.  Mix or stir the seeds frequently until they have turned light brown.  Let them cool, and enjoy.


Sunflowers satisfy everyone in the household.  They are easy to grow.  Their tall stalks and large flowers amaze, their beauty impresses, and their seeds are fun, healthy and tasty.  Best of all, they grow great with hydroponics, so there’s no reason for you to miss out on the fun!

Check Out Our Sunflower Recipes!

Let's grow together!